1. Field of Invention
The present invention relates to dielectric well logging.
2. Description of Prior Art
Prior electromagetic wave logging tools operated at typically from twenty to one hundred megahertz and obtained a measurement of amplitude ratio and phase difference from two receiver coils spaced at different spacings in a sonde from a transmitter coil. These logging tools were usually adequate in determining dielectric constant and resistivity of the formation where drilling fluid invasion has been minimal, so that formation oil and water saturation of the formation could be determined.
When these tools were operated under conditions of moderate to deep invasion, determination of formation dielectric constant and resistivity became very difficult. The presence of the invaded zone, with its effects on electromagnetic fields, caused three more unknown quantities: resistivity and dielectric constant of the invaded zone, and the diameter of invasion. Thus, five unknown quantities were present when these three additional unknown quantities were included with the true formations resistivity and dielectric constant, so that the prior art logging systems did not usually provide adequate data for analysis.